Every random sample of the same size from a given population will produce exactly the same confidence interval for ?.

The standard deviation of the weights of elephants is known to be approximately 15 pounds. We wish to construct a 95% confidence interval for the mean weight of newborn elephant calves. Fifty newborn elephants are weighed. The sample mean is 244 pounds. The sample standard deviation is 11 pounds.

a) Construct a 95% confidence interval for the population mean weight of newborn elephants. State the confidence interval.

b) Calculate the error bound (EBM) for the confidence interval in question 3 (x= average weight)

The U.S. Census Bureau conducts a study to determine the time needed to complete the short form. The bureau surveys 200 people. The sample mean is 8.2 minutes. There is a known standard deviation of 2.2 minutes. The population distribution is assumed to be normal.

a) If the census wants to increase its level of confidence and keep the error bound the same by taking another survey, the census should survey more people.

b) If the census wants to be 98% confident of the population mean length of time, it should survey more people.

c) What would happen if 300 people were sampled instead of 200, and the confidence level remained the same?

A survey of 35 statistics students asked the participants two questions: What is your gender? How many hours did you sleep last night?

The following table of data was created from the results of the survey.